Ellie was searching for one of her lost Mareep when she met Ash and his friends. After finding it, she took them to Floccesy Ranch where she works along with her grandfather Tokuzō. She owns multiple Mareep, which help her with the work on the farm. Her Ampharos is in charge of the Mareep but it was very timid which caused it to have trouble handling them. Ellie decided to have it learn Thunder Punch to avoid the timidness but Ampharos had trouble using it. Iris had her Dragonite train with Ampharos to help it learn Thunder Punch.

When Team Rocket took one of her Mareep, Ellie and the group searched for the missing Mareep but were not successful. They returned to the ranch when it became foggy, only for Ampharos to stay behind. Ellie found the source of the missing Mareep when Pikachu and Axew found Ampharos, which was an electric beam coming from Team Rocket's machine. She battled Team Rocket for a short time and after Pikachu's Thunderbolt and the machine were at full power, her Ampharos and Mareep separated due to the blast. As Team Rocket found the Pokémon first, Ampharos used its lights to get Ellie and the group. With Ellie and Iris's Dragonite's support, Ampharos was ultimately able to master Thunder Punch and defeat Team Rocket. The group returned to the ranch and waved their farewells to Ellie and Tokuzō.

Ampharos is Ellie's main Pokémon. Ampharos tried to help Ellie by giving her Mareep energy, but always failed in doing so. With the help of Iris and her Dragonite, it learned how to use Thunder Punch. When Team Rocket appeared and stole the Mareep, it managed to save them and defeat Team Rocket. At the end of the episode it appeared along with the Mareep at the side of the pathway Ash and his friends were taking, waving goodbye.